105 of the ESS glossary’s terms, each with the part of the syllabus where you first meet it.
A soil rich in calcium carbonate, usually formed on limestone or chalk parent material, with a neutral to alkaline pH.
The process by which organisms such as corals, molluscs and some plankton build shells or skeletons of calcium carbonate from calcium and carbonate ions dissolved in seawater.
A compound of calcium, carbon and oxygen (CaCO₃) that marine organisms use to build shells and skeletons, and the main component of limestone and chalk.
The measurement of the energy content of a material by burning a dried sample completely, often in a bomb calorimeter, and measuring the heat released.
The breeding of animals of a threatened species in zoos or other managed facilities, often with the aim of increasing numbers and reintroducing them to the wild.
A method of estimating the size of a mobile animal population by capturing, marking and releasing a sample, then recording how many marked individuals appear in a second sample.
The total amount of carbon dioxide that can still be emitted while keeping global warming below a chosen limit, such as 1.5 °C, with a stated probability.
A technology that captures carbon dioxide from power stations or industrial sources and stores it permanently, usually deep underground in rock formations, so that it does not reach the atmosphere.
The biogeochemical cycle by which carbon moves between the atmosphere, organisms, soils, oceans and rocks through processes such as photosynthesis, respiration, decomposition, dissolving and combustion.
The total amount of greenhouse gases produced directly and indirectly by a person, product, organisation or country, expressed in tonnes of CO₂ equivalent.
The movement of production and its emissions from a country with strict climate policies to one with weaker policies, which can cancel out the original emission cuts.
A colourless, odourless, poisonous gas (CO) produced by the incomplete combustion of fuels, which reduces the ability of the blood to carry oxygen.
A state in which the carbon dioxide released by a country, organisation or activity is balanced by an equal amount removed from the atmosphere or offset, giving zero net emissions.
A reduction or removal of greenhouse gas emissions in one place, such as tree planting or avoided deforestation, that is paid for to compensate for emissions released elsewhere.
Any policy that makes emitters pay for each tonne of carbon dioxide they release, either through a carbon tax or through an emissions trading scheme.
The process of capturing carbon dioxide from the atmosphere or from emissions and storing it in solid or liquid form, for example in plant biomass, soils, rocks or underground reservoirs.
A tax charged on each tonne of carbon dioxide emitted, or on the carbon content of fuels, which raises the price of high-carbon activities so that emitters have an incentive to cut emissions.
An animal that feeds mainly on other animals, as a secondary or higher consumer.
The maximum size of a population of a species that an environment can support over a long period, determined by competition for limited resources.
A detailed, real example of a place, event, ecosystem or policy, studied in depth to show how general ideas apply and used as specific evidence in extended answers.
A device in a vehicle exhaust in which metal catalysts convert carbon monoxide, unburned hydrocarbons and nitrogen oxides into carbon dioxide, water and nitrogen.
A clouding of the lens of the eye that blurs vision and can lead to blindness; exposure to ultraviolet radiation, especially UVB, increases the risk.
The catch obtained for a standard amount of fishing effort, such as kilograms per hour of trawling, used as an indirect index of the abundance of a fish stock.
A measure of how many positively charged ions, such as calcium, magnesium and potassium, a soil can hold on the negatively charged surfaces of its clay and humus.
A relationship in which a change in one variable directly produces a change in another, shown by a known mechanism and controlled investigation rather than correlation alone.
The process in all living cells that releases energy from glucose and other organic compounds for cell activities, producing carbon dioxide and water and losing some energy as heat.
The set of natural reactions in which ultraviolet radiation splits oxygen molecules into atoms that form ozone, and ozone is broken down again, keeping stratospheric ozone in a steady state.
An autotroph, usually a bacterium or archaeon, that makes organic compounds using energy released by exothermic inorganic chemical reactions rather than light.
The process by which chemoautotrophs make organic compounds from carbon dioxide using energy from oxidising inorganic substances such as hydrogen sulfide.
A statistical test that compares observed frequencies with those expected if there were no association, used to test for an association between categorical variables.
Stable, non-toxic compounds of carbon, chlorine and fluorine once widely used as refrigerants, aerosol propellants, foam-blowing agents and solvents; they release chlorine that destroys stratospheric ozone.
Building in ways that keep materials in use, by designing buildings for disassembly and reuse, using recovered and recycled materials, and avoiding waste in construction and demolition.
An economic model that aims to decouple economic activity from the consumption of finite resources by eliminating waste and pollution, circulating products and materials, and regenerating nature.
The Convention on International Trade in Endangered Species of Wild Fauna and Flora (1973), a treaty that controls international trade in listed species through three appendices of increasing restriction.
Scientific research in which members of the public take part, often by collecting, recording or analysing data, usually in collaboration with professional scientists.
A group of organisms made up of a common ancestor and all of its descendants, which share characteristics inherited from that ancestor.
A branching diagram showing the probable evolutionary relationships between groups of organisms, in which each branching point represents a common ancestor.
The arrangement of organisms into groups on the basis of their shared characteristics, which allows efficient identification and the prediction of other characteristics.
The finest mineral fraction of soil, with particles smaller than 0.002 mm, made of complex silicate minerals that hold water and positively charged nutrient ions.
The average atmospheric conditions of a place, such as temperature, precipitation, humidity and wind, calculated over a long period, usually about 30 years.
Distress, worry or fear about climate change and its threat to the future, which can affect people's feelings, thoughts and daily functioning, especially among young people.
Long-term changes in the Earth’s climate, including global warming and the wider changes it causes in rainfall, extreme weather, ice cover, sea level and ocean conditions.
Adjustment of human or natural systems to actual or expected climate change, reducing its harmful effects and making the most of any beneficial ones.
Action that reduces the causes of climate change by cutting greenhouse gas emissions, removing greenhouse gases from the atmosphere or reducing the warming process itself.
A graph showing the average monthly temperature of a place as a line and its average monthly precipitation as bars, usually based on about 30 years of data.
An approach to climate change that treats it as an ethical and political issue, asking that responsibility, costs and help be shared fairly given that those least responsible are often most vulnerable.
Legal action in national or international courts to force governments or companies to reduce greenhouse gas emissions, adapt to climate change or pay for climate-related harm.
A computer simulation that uses mathematical equations for the physical, chemical and biological processes of the atmosphere, ocean, land and ice to reproduce past climate and project future climate.
Doubt or denial that climate change is happening, that it is caused mainly by human activity, or that it is serious enough to justify action.
The degree to which a community, country or ecosystem is likely to be harmed by climate change, depending on its exposure, sensitivity and capacity to adapt.
The relatively stable community at the end of a succession, in steady-state equilibrium with the climate and soils of the area.
A survey question with a fixed set of possible answers, such as yes or no, multiple choice or a Likert scale, giving data that can be counted.
A period during which fishing for a species is banned, usually timed to protect it while it spawns or while its young grow.
A system that exchanges energy but not matter with its surroundings; Biosphere 2 and, approximately, the Earth and its global cycles are examples.
A weather modification technique in which particles such as silver iodide or salt are released into clouds to encourage water droplets or ice crystals to form and fall as precipitation.
A unit that expresses the amount of any greenhouse gas as the amount of carbon dioxide that would cause the same warming, so different gases can be added together.
The square of the correlation coefficient, R², giving the proportion of the variation in the dependent variable accounted for by its linear relationship with the independent variable.
The attraction of water molecules to each other through hydrogen bonds, which gives water its high surface tension and lets it be pulled up through plants in columns.
The arrival and establishment of a species in an area where it did not previously live, for example plants spreading onto newly exposed rock.
The burning of a fuel or organic matter in oxygen, a transformation that releases energy as heat and light and returns stored carbon to the atmosphere as carbon dioxide.
Farming in which crops or livestock are produced mainly for sale in markets to earn a profit, rather than for the farmer's own household.
An ancestral species from which two or more later species or groups have evolved, shown as a node on a cladogram.
The principle that all states share responsibility for protecting the global environment, but that richer states, which have caused more damage and have more resources, should take on greater obligations.
A resource that many people can use, where it is difficult to exclude users and each person's use reduces what is left for others, such as ocean fish stocks, groundwater or common grazing land.
A collection of interacting populations of different species living in the same area at the same time.
The squeezing together of soil particles, for example by heavy machinery or trampling, which reduces pore space, aeration, infiltration and root growth.
An interaction in which organisms of the same or different species need the same limited resource, such as food, water, light or space, so that each gets less.
The aerobic decomposition of organic waste, such as food scraps and garden waste, by microorganisms into compost, a stable, humus-rich material used to improve soil.
The transformation of water vapour into liquid water droplets when air cools, which releases latent heat and forms clouds, fog and dew.
The annual meeting of all the countries that are party to the UNFCCC, where climate agreements are negotiated and progress is reviewed.
An ethical approach in which an action is right if it produces the best overall consequences, regardless of the intentions behind it.
The protection, management and sustainable use of species, habitats and ecosystems so that biodiversity and the services it provides are maintained for the present and the future.
A measure of how likely a species is to become extinct in the near future, assessed against standard criteria and expressed as a category such as Vulnerable or Critically Endangered.
An organism that obtains its energy and carbon compounds by feeding on other organisms or their remains, rather than making its own food.
A temperate climate type far from the sea, with a large annual temperature range, cold winters, warm or hot summers and lower precipitation, often peaking in summer.
A survey method that estimates the value of a non-market good by asking people their willingness to pay for it, or to accept compensation for its loss, in a described scenario.
A way of managing forest in which trees are harvested selectively or in small groups, so the canopy and soil are never fully cleared.
Ploughing across a slope along its contours, so that each furrow slows run-off and reduces soil erosion by water.
A factor that could affect the dependent variable and is kept constant, or as constant as possible, so that changes can be attributed to the independent variable.
Choosing survey respondents because they are easy to reach, such as classmates or passers-by at one place and time; quick but likely to be biased.
A broad international agreement, legally binding on the states that ratify it, which sets out general goals and a framework for cooperation on an issue, such as the UNFCCC.
A United Nations treaty opened for signature in 1992 whose objectives are the conservation of biodiversity, the sustainable use of its components and the fair sharing of benefits from genetic resources.
The whitening of corals when heat or other stress causes them to expel the symbiotic algae living in their tissues, leaving them without their main food source and at risk of death.
A shallow, warm-water marine ecosystem built from the calcium carbonate skeletons of corals, with very high productivity and species diversity despite nutrient-poor surrounding water.
The strictly protected central part of a biosphere reserve, where ecosystems are left largely undisturbed and only monitoring and low-impact research are allowed.
The apparent deflection of moving air and water caused by the Earth's rotation: to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
A statistical relationship in which one variable tends to increase (positive) or decrease (negative) as another increases; it does not by itself show causation.
A number from −1 to +1 measuring the strength and direction of a correlation between two variables, with 0 meaning no correlation.
A method of appraising a project or policy by estimating all its costs and benefits in money, including environmental ones where possible, and comparing the totals.
A crop, such as clover, rye or vetch, grown mainly to cover and protect bare soil between main crops rather than to be harvested.
A mineral that is essential to important technologies, such as batteries, magnets and electronics, and whose supply is at risk because production or processing is concentrated in few countries.
The value of a test statistic, read from a table for a chosen significance level and degrees of freedom, that the calculated statistic must exceed for significance.
The IUCN Red List category for species facing an extremely high risk of extinction in the wild, for example with fewer than 50 mature individuals or a decline of 80–90% or more over ten years or three generations.
Growing a different crop on the same field in successive seasons in a planned sequence, often including a legume, to maintain fertility and break pest cycles.
A charge on imported goods according to the carbon dioxide emitted in making them, so that producers in countries without a carbon price cannot undercut those that pay one.
The number of live births per 1,000 people in a population per year, calculated from the total (usually mid-year) population without allowing for its age or sex structure.
The number of deaths per 1,000 people in a population per year, calculated from the total (usually mid-year) population without allowing for its age structure.
All the frozen water of the Earth system, including ice sheets, glaciers, sea ice, snow cover and permafrost.
The planned use of fire by Indigenous people according to traditional knowledge to manage land, such as lighting small, cool fires early in the dry season to prevent large late-season wildfires.
Non-material benefits that people obtain from ecosystems, such as recreation, tourism, beauty, spiritual meaning, education and a sense of place.
The worth of natural capital to the identity, traditions, history and way of life of a group of people, such as a traditional harvest or a landmark central to local customs.
The total amount of a greenhouse gas, usually carbon dioxide, emitted by a country or the world over a long period, typically since the Industrial Revolution.
The use of sodium cyanide sprayed onto coral reefs to stun fish for capture, mostly for the live reef-fish food and aquarium trades, which kills coral and non-target animals.
Photosynthetic bacteria, often called blue-green algae, that can form dense blooms in nutrient-rich water; some species produce toxins.
A toxin produced by cyanobacteria, such as microcystin, which damages the liver, that can poison people and animals that drink or swim in affected water.